The Nanjing Fiat 1. 5L car with a mileage of about 68 thousand km. User reflection: the vehicle is unable to start. Fault diagnosis: according to the fault reflected by the owner, the maintenance technician first confirms the fault. It is found that the starting machine can run when the vehicle is started, but it is unable to run, and the engine can not start at all. According to the fault symptoms of the car, it is suspected that the battery capacity is insufficient. The battery was tested by the battery tester, but the battery was completely normal after testing. Since the battery is normal, will it be a problem with the starter itself? Considering that the battery and the starting machine are connected by a thicker power line, if the resistance of the power line is too large, the voltage drop of the starting machine is too large to make the starting machine overvoltage so that the starting machine can not be driven. For this reason, the maintenance technician measured the voltage at the starting machine when the vehicle started, and found that the voltage was too low. After the replacement of the power line. Then restart the engine, the vehicle starts smoothly, and the trouble is completely eliminated.